Qubes, a Linux OS, uses Xen to spawn multiple domains and promises to reduce risk with some extra effort. For most of us, the effort would be better spent elsewhere
Qubes is a Fedora-based Linux OS running on Xen, a bare-metal hypervisor. Qubes' most interesting feature is the ability to run one or more security domains, each of which operates in a separate, lightweight virtual machine environment. The idea is to provide a more secure OS in which it's highly difficult for one exploited app or environment to impact apps or environments that reside in different security domains.